The energy required for breaking high intensity currents is provided by the arc which causes a large temperature rise in the gas and thus a large increase in its pressure. Energy stored in this manner is used to facilitate blasting the arc.
When the current to be interrupted is of small intensity, the energy developed by the arc is likewise small, and there comes a point where insufficient energy is released to break the circuit. It is therefore necessary to include auxiliary mechanical gas compressing means to act in the final stages of circuit breaking.
Preferred embodiments of the present invention provide break chambers capable of breaking currents at any intensity up to a maximum, while expending little energy.